黄土山地典型覆被类型对土壤水分运动的影响

Effects of Typical Land-cover Types on Soil Water Movement in Loess Mountainous Land

黄土高原山区土地覆被发生了巨大变化,为研究退耕还林后,覆被类型对黄土高原土壤水分的影响,对典型覆被类型的山区土地开展了不同季节土壤含水率变化监测研究。结果表明,不同深度土壤水分随季节发生了较大的变化,而相同季节不同的覆被类型对降水入渗及土壤水运动也有极大影响,且对土壤水分有效性有显著影响。植树造林有利于林地0~3 m土壤水的补给,但仍会出现土壤干层,且下部土壤水的补给明显受到该干层的影响。覆被类型不同,土壤水分的变化趋势不同,当土壤水分改变后,又反作用于植被。土壤水与植被之间存在一个平衡状态,当平衡状态被打破时,直接影响植被的生长,而影响土壤水分的运动。

Great changes have been taken place in the land-cover types of the Loess Plateau.The changes of soil moisture was monitored in different seasons in mountainous land covered by cultivated land,fallow land and apricot orchards.The purpose of this study is the influence of the land-cover types to precipitation infiltration and soil water movement effects on soil moisture in mountainous of the Loess Plateau after returning farmer-land to forests.The results show that soil moisture at different depth change greatly in different seasons.In the same season,different cover types have a great influence on the precipitation infiltration,soil water movement and soil water availability.The supply of soil waters in mountainous land of the Loess Plateau are enhanced at depth of 0 ~ 3 m after the period of returning farmer-land to forests.However,dried soil layer is detected in the study area covered by apricot orchards and soil water under dried soil layer is affected by this layer.Different land-cover types bring different the soil moisture change trend.When the soil moisture change,and reaction is coming in vegetation.There are an equilibrium state between soil water and vegetation.Once it is broken,not only the growth of vegetation is directly affected,but also the effect of soil moisture movement.